Expanding chuck



April 12, 1949.

s. H. STUPAKOFF ET AL 2,466,974

EXPANDING CHUCK Original Filed Dec. 9, 1942 2 Sheets-Sheet 1 IllINVENTORS SBmon If Stup akoff M liawsan Star M W ATTORNEYS April 12,1949. s. H. STUPAKOFF ET AL EXPANDING CHUCK Original Filed Dec. 9, 19422 Sheets-Sheet 2 i YIIIIJI' m E 9 .20 19 19 ll y w 2" mi 11 ATTORNEYSPatented Apr. 12, 1949 UNITED STATES PATENT OFFICE EXPANDING CHUCKOriginal application December 9, 1942, Serial No.

468,411. Divided and this application November 17, 1945, Serial No.629,218

4 Claims.

In accordance with the present invention, there are provided certainimprovements in work-holding instrumentalities, which instrumentalitiesare designed especially for mounting on a lathe of a type that isintended for use in the manufacture of coil forms made of ceramiccompositions, such as steatite porcelain, for example, although it willbe understood that the instrumentalities of the present invention arenot limited to such adaptation.

Various types of radio equipment require insulating cores or forms aboutwhich wire is wrapped to form an inductance. Extreme accuracy isrequired in such devices. The surface of the core or form is threaded toreceive the convolutions of wire and hold them in spaced relation. Theforms must be of a predetermined fixed diameter which must be adhered towithin very close tolerances and they must be of predetermined length.In some cases it is necessary that the core be frustro-conical in shapeor that a portion thereof be tapered.

The present invention provides a work-holder for holding blanks of aceramic composition of the above-indicated character, from which blanksthe cores are produced, the work-holder being especially suitable formounting on a lathe intended for performing work of the above-indicatedcharacter. The lathe and work-holder are designed so that the work-piececan be mounted quickly and readily thereon, the necessary machiningoperations performed, and the resulting piece easily removed. Provisionis made whereby the thread-cuttin operation will begin at apredetermined point and terminate at another predetermined point.Provision is also made whereby the part may be very quickly and rapidlyreduced to its desired diameter or contour and cut oif to the desiredlength, the arrangement being such that the cutting off operation can beperformed at only predetermined definite points, This prevents theoperator from spoiling the piece by cutting it in the wrong place. Whilethe holder of the present invention will be shown and described inconnection with a lathe adapted to perform the above-indicatedoperations, it will be understood that this adaptation is by way ofillustration and example only, and that the workholder of the inventionis adapted to any adaptation wherein predetermined machining operationsof the above-indicated type are to be performed.

The invention may be understood more readily by reference to theaccompanying drawings, in which:

Fig. 1 is a front elevation of an assembly of the 2 chuck of the presentinvention mounted on driving instrumentalities for rotating the chuck,with a work-piece, fragmentarily shown, mounted on the chuck;

Fig. 2 is a detailed view, partly in section and partly in elevation, ofone form of the chuck of the present invention adapted to hold theworkpiece shown in Fig. 1;

Fig. 3 is a view similar to Fig. 2, showing the chuck expanded withinthe work-piece;

Fig. 4 is a front view, partly in section and partly in elevation, of amodification of the chuck assembly shown in Fig. 1; and

Fig. 5 is a fragmentary view, partly in section and partly in elevation,of another form of the chuck assembly shown in Fig. 4.

Referring more particularly to the drawings, and first to Fig. 1,reference character A designates a frame provided with head stocks B andB through which passes a shaft C, on which is mounted a pulley wheel D,this being adapted to be driven from a suitable driving mechanism (notshown) for rotating the shaft.

On the opposite end of the shaft is a workholding chuck or mandrel,designated generally at 9, which may be in the form as shown in Figs. 2and 3; as illustrated in these views, the shaft C has a transverse pintherethrough at the inner end of the mandrel. Forwardly of this pin themandrel or shaft has a portion ll of reduced diameter along which is akey-way l2. There is a series of expansible collars l3 fitted about theportion II and between each two expansible collars is a metal ring M,which ring is provided with a pin I5 that enters the key-way l2 so thatthe collars l4 rotate with the spindle but are free to slide along onthe spindle. The outermost end of the spindle is threaded, as indicatedat IE, to receive a knurled nut ll. This nut bears against the endmostrubber collar [3. When the nut I1 is turned relatively to the spindle,its inner end presses against the first rubber collar. This, in turn,presses against the first metal ring I4, which again in turn transmitspressure to the second rubber collar. From the second rubber collarpressure is transmitted through the second ring M to the third rubbercollar. With this arrangement, all of the rubber collars maybe equallyexpanded, as indicated in Fig. 3.

The work-piece, designated specifically as 9 in Fig. 3, has an internaldiameter slightly larger than the normal diameter of the mandrel. It isslipped over the mandrel until its inner end contacts the cross pin 10.Then the nut I1 is turned to expand the rubber collars. Due to the factthat the metal rings l4 between the rubber 3 collars are keyed to theshaft and frictionally press against the rubber, the rubber collarscannot turn relatively to the spindle. The workpiece thus isfrictionally held by the rubber collars to rotate with the spindle.

In order to remove the work-piece, the nut I1 is turned in the oppositedirection and the resilience of the rubber rings causes the mandrel tocollapse. This operation of mounting the workpiece on the mandrel can beperformed very quickly and rapidly and does not require a skilledmachinist to apply and remove the work-piece.

Fig. 4 shows a modification of the chuck assembly of Fig. 1. In thismodification, the shaft C' has been bored longitudinally to provide forthe insertion of the rod 20, which rod is threaded at its left end toengage the wing nut 22. A cap or other abutment 21 is secured to theright end of the rod 20 by flattening or riveting the projecting end ofthis rod against the head of the cap 2|, as shown, or by other suitablemeans of fastening. The internal diameter of the cap 2i is such as toenable it to slide easily over the outer end of the reduced portion llof the shaft. An operating device for the rod, such as a wing nut 22 atthe left end of the shaft is provided, and by tightening this nut thecap 21 is drawn to the left so as to exert longitudinal pressure againstthe rubber and metal ring assembly and thus effect the radial expansionof the rubber collars.

In Fig. 4 there is also shown, in section, a further modification of thechuck of Fig. 2. This modification consists of mounting the rubbercollars 13' upon metal sleeves I 9, the length of these metal sleevesbeing less than the length of the rubber collars, so that the rubbercollars overlap the metal sleeves. Hence, when the rubber collar islongtiudinally compressed it will tend to buckle radially so as toengage the hollow workpiece, but, by reason of the metal sleeve 19, anytendency of the rubber collar 13 to bind against the shaft II will beprevented.

In Fig. 5 there is shown a small cross sectional view of a modificationof the work-holding mandrel of Fig. 4. In this modification the metalrings 14" are reamed out at both ends so as to provide annular abutmentsor rims, designated as l8, which are used to transmit longitudinally thepressure exerted by the combined action of the cap 2 and the wing nut 22for the radial expansion of the rubber collars 13''. As in Fig. 4, therubber collars 13" are again mounted upon metal sleeves 19', but, inFig. 5, the length of the metal sleeves is made greater than that of therubber collars, in contradistinction to Fig. 4. As shown, the properprecaution has been taken in the design of the metal rings and metalsleeves as to clearance, so as to prevent the metal sleeves from{blocking off the longitudinal transmission of pressure along the shaftfor radial expansion of the rubber collars.

Although Figs. 1 to 3 have shown a nut threaded on the end of the shaftand Figs. 4 and 5 have shown an endwise movable abutment on the shaftoperating with means at the opposite end of the shaft, it is understoodthat these arrangements will be interchangeable in the respectivemodifications.

It is evident that the specific embodiments of the invention as shown inthis specification are merely by way of illustration, and it is notdesired to restrict the scope of the invention thereto.

This application is a division of our application, Serial No. 468,411,filed December 9-, 1942, now Patent No. 2,392,427.

We claim:

1. A work-holder for holding hollow workpieces, comprising a hollowshaft, a plurality of rings splined on the shaft whereby they may beadjusted longitudinally of the shaft but rotate with it, a plurality ofsleeves on the shaft interposed between the rings, a rubber collarcarried by each of the sleeves, a rod positioned inside the shaft, therod having a cap secured to its one end for slidable engagement over theone end of the shaft for abutment of the ring and rubber collar assemblyon the shaft, and said rod having a threaded portion at its opposite endfor engagement with a nut abutting the opposite end of the shaft, meansfor rotation of the nut for radial expansion and contraction of the ringand rubber collar assembly.

2. A work-holder for holding a hollow workpiece comprising a shaft, aplurality of spaced expansible collar elements on the shaft, spacingrings intermediate the expansible collar elements and through whichendwise pressure may be transmitted from one expansibl'e collar elementto another to expand the same, an abutment on one end of the shaft overwhich work-pieces may be slipped to encircle the collars, a rod passingthrough the shaft and connected with the abutment for forcing theabutment endwise of the shaft to apply pressure to or release pressurefrom the collars, and means at the opposite end of the shaft foroperating same.

3. A work-holder for holding a hollow workpiece comprising a shaft, aplurality of spaced sleeve elements on the shaft, a plurality ofexpansible collar elements carried by the sleeve elements, spacing ringsintermediate the expansible collar elements and through which end- Wisepressure may be transmitted from one expansi-ble collar element toanother to expand the same, and adjustable means on the end of the shaftand over which work-pieces may be applied and removed for applyingendwise pressure to the collar and ring elements for operating thedevice.

4. A work-holder for holding a hollow workpiece comprising a shaft,a'plurality of spaced sleeve elements on the shaft, a plurality ofexpansible collar elements carried by and encircling the sleeveelements, spacing rings intermediate the. expansible collar elements andthrough which endwise pressure may be transmitted from one expansiblecollar element to another to expand the same, an abutment on one end ofthe shaft over which work-pieces may be slipped to encircle the collars,and means at. the same end of the shaft for forcing the abutment endwiseof the shaft to apply pressure to or release pressure from the collar.

.Slt'lVfON H. S'I'UPAKOFF. RAWSON E. STARK.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 163,217 Lawson May 11, 1875574,763 Rudolph Jan. 5, 1897 780,850 Williams Jan. 24, 1905 1,479,253Rivetta Jan. 1, 1924 FOREIGN PATENTS Number Country Date 109,231 GreatBritain Sept. 6,, 1,917

